I'm currently using a G1 and I find it very comfortable using it, so changing to a glayzer seems like a step down because they are pretty similar but glayzer is slower
Glayzer seems like a step down? How?
And how can you say they are pretty similar? Have you already tried the Glayzer?
I don't think Glayzer is slower that G1.
Slower on slow shots (maybe?) but when putting real power into the stroke then I would wager that the Glayzer may actually be faster.
My main point though, is about choosing a rubber that works best for you.
However it seems you are intent on buying the 'best' rubber available no matter what.
Absolutely nothing wrong with that, it's your money\time etc and hopefully you'll have fun figuring it all out but I personally cannot see D05 working for you.
I think you a have fallen victim to the EJ thinking that the way to improve your shots further is to buy better and faster equipment.
As so many have found out, this is not really the case.
For a coach to tell you that a rubber like G1 or Glayzer is the limiting factor in your game and that it's literally holding you back (and D05 could see you move fwd) you would be at the level where you wouldn't be asking these questions.
Imo you would be better to stay with G1 until your FH technique is perfect.
Anyway, have fun whatever you do and good luck 👍